Best Practices for Installation of Gaseous Sample Pumps

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Sylvia Chase
5 years ago
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1 Best Practices for Installation of Gaseous Sample Pumps

2 Goal of the Gas Sample Pump Transport a clean, reliable, sample of the process gas to the analyzer, in the safest and easiest way possible, to ensure accuracy and reliability.

Required information to ensure proper pump selection For most gas sampling applications, the following information is required to determine the pressure drop and proper pump selection: Sample point

3 Required information to ensure proper pump selection For most gas sampling applications, the following information is required to determine the pressure drop and proper pump selection: Sample point conditions atmospheric, vacuum, or positive pressure Analyzer pressure requirements Endpoint considerations (Vent to Atmosphere or return back to process) Required Flow Rate or Response Time Temperature and Type of Gas being pumped Ambient temperature where pump will operate Distance and diameter of tubing Voltage, frequency, and electrical classification (Safe area, Division I, Division II)

4 Pump Location and Line Sizing is Key SIZE I.D. Line Press Drop - Pos A Line Press Drop - Pos B 1/4 x.035 wall.180 inch 20.0 PSIA PSIA = 5.3 PSID 14.7 PSIA 7.3 PSIA = 7.4 PSID 3/8 x.035 wall.305 inch 15.0 PSIA 14.7 PSIA =.3 PSID 14.7 PSIA 14.3 PSIA =.4 PSID

5 Pump Location and Line Sizing is Key Response time Flow rate and total volume Pressure Drop Comparing tubing pressure drops for pressurized and vacuum sample line conditions illustrates the importance of line size; in addition, a larger displacement pump may be required for smaller line sizes because of vacuum conditions and decrease density. Vapor condensation may be a problem if pump is located a long distance from process inlet and sample pressure is reduced below gas vapor pressure. Final selection of line size and pump location is effected by many factors, including local codes, environmental considerations, system design, and installation requirements.

6 Flow and Pressure Control Configuration A Flow rate reduced by increased restriction by Throttle Valve TV, resulting in pressure reduction at pump inlet. With TV closed, Pa will decrease to less that 14 PSIG. Configuration B Flow rate reduced by increased restriction by TV, increasing pressure at pump outlet up to maximum of pump capacity. Depending on pump characteristics, pressure increase at Pb may range from 30 PSIG to 100 PSIG or more. Summary Excessive pressure on pump diaphragm (Configuration B) will result in increased diaphragm and bearing stress, reducing pump life and increasing service requirement.

7 Flow and Pressure Control RV FI Pump TV Relief valve reduces high pressure pulses on pump diaphragm, flow pulses will be reduced; return line may be connected to process or pump inlet. (Lowest Cost)

8 Flow Pulsations Addition of a filter at the inlet & outlet will reduce the pump outlet pressure pulse amplitude. This is important when flowmeters or other pressure-sensitive instrumentation is used, as pulsation will give false readings.

Double Head Pump in Parallel When the inlet and outlet ports of the two heads are connected in parallel, there will be continuous action at the interconnect junctions and no dead time between inlet

9 Double Head Pump in Parallel When the inlet and outlet ports of the two heads are connected in parallel, there will be continuous action at the interconnect junctions and no dead time between inlet or outlet pulses. The result of this design is smoother gas flow with greatly reduced pulsation effects at the inlet and outlet connections; in addition, sample line pressure losses are correspondingly reduced because of the reduced peaked and nearly-constant flow rate.

10 Double Head Pump in Parallel When the inlet and outlet ports of the two heads are connected in parallel, there will be continuous action at the interconnect junctions and no dead time between inlet or outlet pulses. The result of this design is smoother gas flow with greatly reduced pulsation effects at the inlet and outlet connections; in addition, sample line pressure losses are correspondingly reduced because of the reduced peaked and nearly-constant flow rate.

Liquid Considerations For applications where there is potential for liquid to

Heat the pump head and line to prevent condensation.

11 Liquid Considerations For applications where there is potential for liquid to enter the pump head; it is advised to mount the pump in such a way so that the discharge port faces toward the ground. Mount pump as high in the sample system as possible. Heat the pump head and line to prevent condensation. Gas Cooler, Membrane Filters to remove liquids Vapor condensation may be a problem if pump is located a long distance from process inlet and sample pressure is reduced below gas vapor pressure.

12 Diaphragm Pump Maintenance

13 Ease of Maintenance

14 Eccentric Sizing for Performance and to extend diaphragm and bearing life.

15 Selection of Wetted Parts With most CEMS gases, Teflon-coated Aluminum wetted parts and Teflon-coated EPDM diaphragms are suitable. In some acidic samples, 316ss and All-Teflon diaphragms should be used. Additional Options Hastelloy C Solid Teflon Teflon-coated 316ss and Hastelloy C

16 ADI Pump Options Class I Division I Group B/C/D Explosion proof (UL & CSA) Class I Division II Group A/B/C/D Hazardous Area (UL) IP ratings 44, 54, 65, & Marine Duty. 115v/230v 1 phase, 3 phase 230/460v, Air Driven Heated head for safe areas Elevated & Steam traced heads for hazardous areas Corrosion resistant 316ss, Hastelloy C, Teflon-coating, Silconert 2000 All pumps ship out in 1-2 days

17 Thank you for your time. Chris Williamson Air Dimensions Incorporated. We pass your gas!

DIAPHRAGM VACUUM PUMPS AND COMPRESSORS

DIAPHRAGM VACUUM PUMPS AND COMPRESSORS DATASHEET N 2400 N 2400.15 ST.9 E Concept The diaphragm pumps from KNF arebased on a simple principle an elastic diaphragm, ixed on its edge, moves up and down its